I had a horrid feeling I’d just met the ‘gentlemen visitors’ that Kim had warned me about.

Where had they come from? I doubted they’d sauntered here from the tube station. I glanced up the road and spotted a black Ford Explorer hiding amongst the other Chelsea Tractors. It had the traditional tinted windscreen but we could still make out the figure of a white guy in the driver’s seat.

‘Can’t leave him there,’ said Guleed.

She was right. If we went in after the goon squad, their man in the Explorer would tip them off. So we quickly concocted one of our better plans – better insofar as that just for once it went as planned.

I approached on the pavement while Guleed strolled up the middle of the street and caught the driver’s attention. As soon as she had it, she pulled out her warrant card and held it up as she advanced. We’d both decided that when dealing with a possibly armed American it was better to avoid any potential ambiguity.

‘Especially since I’m the one being ambiguous,’ said Guleed.

The driver might have sussed me for police as well, but it didn’t matter. He hesitated for long enough for me to slap a car killer into the bonnet of the Explorer and that’s all she wrote for that particular electronic ignition system. I kept it low key enough to avoid frying any phone he might be carrying – just in case we might need it later.

Because he was American, he instinctively kept his hands on his steering wheel where we could see them.

‘Good evening, sir,’ said Guleed. ‘Would you step out of the car, please?’

And that was that.

He got out and we conducted a search in full compliance with Code A, Paragraph 3.1 of the Code of Practice – to whit, that all searches must be carried out with courtesy, consideration and respect for the person concerned.

Apart from, sensibly, keeping his mouth shut he cooperated with the search. Which was just as well because he was tall and fit and carrying a semi-automatic pistol in a shoulder holster. He also had a Samsung Galaxy with a retro modded hard ‘off’ switch not entirely unlike the phones me and Nightingale carried. And when I checked his wrist I saw he had a wind-up diver’s watch. It was practitioner’s gear and, coupled with the absence of anything identifiable on his person – not even a driver’s licence – pretty much confirmed that these were magic spooks. They might even have some legal standing in the states.

But not in London, so Guleed arrested him for carrying a firearm, driving without a licence and being suspiciously foreign in a built-up area. By the time we had him cuffed, the first IRV had arrived and we cheerfully handed him over to be tucked up in the back.